指向 C++ 中的 object 的指针

Question

I have a question about pointer to a object in C++.
For example, if we have a CRectangle class and there is ay variable in it.

CRectangle *x = new CRectangle;

x->y means member y of object pointed by x, what about (*x).y ? are they the same?

Answer 1

Yes, x->y and (*x).y are exactly the same in your example. The -> means dereference X, and *x means exactly the same.

Answer 2

Yes, (*x).y is equivalent to x->y if x is of a pointer type.

Answer 3

Yes. You can see it by yourself with this sample program:

#include <iostream>
using namespace std;

class CRectangle {
    int width, height;
    public:
    void set_values (int, int);
    int area (void) {return (width * height);}
};

void CRectangle::set_values (int a, int b) {
    width = a;
    height = b;
}

int main () {
    CRectangle r1, *r2;
    r2= new CRectangle;
    r1.set_values (1,2);
    r2->set_values (3,4);
    cout << "r1.area(): " << r1.area() << endl;
    cout << "r2->area(): " << r2->area() << endl;
    cout << "(*r2).area(): " << (*r2).area() << endl;

    delete r2;
    return 0;
}